1. Field of the Invention
The present invention relates to a hermetically sealed rectangular battery having a metallic can such as alkaline storage battery. More particularly, the present invention relates to a laser welding-sealed type hermetically sealed rectangular battery.
2. Description of the Related Art
In recent years, there has been a remarkable development of portable apparatus using battery. Video camera, portable telephone, etc. have been aggressively marketed. The batteries to be used as power supply for driving these apparatus are facing demand for higher capacity, smaller size and lighter weight. In order to meet these demands, small-sized hermetically sealed rectangular batteries having a rectangular can instead of cylindrical can have been used more and more for the purpose of reducing the battery size and hence saving the battery space.
As shown in FIG. 4, such a hermetically sealed rectangular battery is normally prepared by a process which comprises receiving a group of electrode plates having a positive electrode plate and a negative electrode plate laminated on each other with a separator provided interposed therebetween in a metallic can having an upper side, a bottom, a pair of opposing wide sides and a pair of opposing narrow sides in such an arrangement that the direction of lamination of the group of electrode plates is perpendicular to the wide side of the metallic can, injecting an electrolytic solution into the metallic can, placing a sealing plate 1 provided with a positive electrode terminal 2 as shown in FIG. 5 on an opening formed in the upper side of the rectangular can, and then laser-welding the sealing plate 1 to the rectangular can.
FIG. 5 generally illustrates a sealing body 10 provided with a conventional positive electrode terminal. The reference numeral 1 indicates a sealing plate, the reference numeral 2 indicates a positive electrode terminal, the reference numeral 3 indicates a gasket, and the reference numeral 4 indicates a laser-welded portion.
However, the sealing plate 1 provided with one of the two polarities as shown in FIG. 5 is disadvantageous in that the distance between the laser-welded portion 4 and the gasket 3 is so small that the gasket can be melted during laser welding, causing the deterioration of the airtightness of the battery resulting in easy occurrence of electrolyte leakage. In particular, under the present status of quo that there is a growing demand for the reduction of the thickness of such a type of rectangular battery, the distance between the laser-welded portion 4 and the gasket 3 cannot be increased in an attempt to prevent the gasket from being melted during laser welding. Further, further reduction of the thickness of such a type of rectangular battery is limited.
The present invention has been worked out in the light of the foregoing problems. An object of the invention is to provide a hermetically sealed rectangular battery which is little liable to melting of gasket during laser welding causing the deterioration of the airtightness of the battery as well as to occurrence of electrolyte leakage and accomplish further reduction of the thickness of such a hermetically-sealed rectangular battery.
Namely, a first aspect of the battery is a hermetically sealed rectangular battery, which comprises a group of electrode plates received in a metallic can having a pair of opposing wide sides and a pair of opposing narrow sides, said group of electrode plates having a positive electrode plate and a negative electrode plate laminated on each other with a separator provided interposed therebetween, wherein said metallic can is provided with a terminal which connects with an electrode plate of said positive electrode plate and negative electrode plate on the wide side thereof.
A second aspect of the battery is a hermetically sealed rectangular battery according to the first aspect, wherein the terminal is mounted on a sealing plate of said metallic can.
A third aspect of the battery is a hermetically sealed rectangular battery, according to the second aspect, wherein the terminal is mounted through a gasket on the sealing plate, and said metallic can is connected with other one electrode plate of said positive electrode and negative electrode.
A fourth aspect of the battery is a hermetically sealed rectangular battery, according to the second aspect, wherein the sealing plate is mounted on a recess formed on the wide side of said metallic can.
A fifth aspect of the battery is a hermetically sealed rectangular battery, according to the second aspect, wherein the sealing plate comprises:
a main sealing body portion mounted on the wide side of said metallic can so as to be in parallel with the wide side, on which the terminal is mounted on a recess formed on the wide side of said metallic can;
a first sealing portion extended from one side of the main sealing body portion so as to be folded in a perpendicular direction to the main sealing body portion; and
a second sealing portion extended from one side facing to said side of the main sealing body portion so as to be folded in an opposite direction to said direction to the main sealing body portion, and
free ends of said main sealing body portion, said first sealing portion and said second sealing portion are sealed with said metallic can.
A sixth aspect of the battery is a hermetically sealed rectangular battery, according to the fifth aspect, wherein said sealing plate and said metallic can are sealed with each other by laser welding.
A seventh aspect of the battery is a hermetically sealed rectangular battery, according to the second aspect, wherein said hermetically sealed rectangular battery is a hermetically sealed rectangular alkali storage battery.
An eighth aspect of the battery is a hermetically sealed rectangular battery, according to the seventh aspect, wherein said hermetically sealed rectangular battery is a hermetically sealed rectangular nickel-hydrogen storage battery.
A ninth aspect of the battery is a hermetically sealed rectangular battery, according to the seventh aspect, wherein said hermetically sealed rectangular battery is a hermetically sealed rectangular nickel-cadmium storage battery.
A tenth aspect of the battery is a hermetically sealed rectangular battery, according to the second aspect, wherein said hermetically sealed rectangular battery is a hermetically sealed rectangular lithium battery.
A eleventh aspect of the battery is a hermetically sealed rectangular battery, according to the second aspect, wherein said hermetically sealed rectangular battery is a hermetically sealed rectangular lithium ion secondary battery.
The hermetically sealed rectangular battery of the invention comprises a group of electrode plates received in a metallic can having a pair of opposing wide sides and a pair of opposing narrow sides, the group of electrode plates having a positive electrode plate and a negative electrode plate laminated on each other with a separator provided interposed therebetween, characterized in that the metallic can is provided with a terminal which also acts as an electrode of one of the two polarities disposed on the wide side thereof.